Sustainable attempts have been made in the fields of academy and industry to prepare a polyolefin with desired properties using a variety of homogenous catalysts since Prof. Kaminsky developed the homogeneous Ziegler-Natta catalyst using a Group 4 metallocene compound activated with a methylaluminoxane co-catalyst in the late 1970's.
The conventional heterogeneous catalysts in ethylene/α-olefin copolymerization not only provide a low quantity of α-olefin incorporation but cause the α-olefin incorporation to occur primarily in the polymer chain with low molecular weight only. Contrarily, the homogenous catalysts in ethylene/α-olefin copolymerization lead to induce a high quantity of α-olefin incorporation and provide uniform α-olefin distribution.
In contrast to the heterogeneous catalysts, however, the homogenous catalysts are hard of providing a polymer with high molecular weight.
With low molecular weight, the polymers encounter a limitation in development of their usage, such as being inapplicable to the products required to have high strength. For that reason, the conventional heterogeneous catalysts have been used in the industrial manufacture of polymers, and the usage of the homogeneous catalysts is confined to the manufacture for some grades of polymer.
Since the mid-1980's, the metallocene catalysts have been used to prepare a polyolefin with narrow molecular weight distribution and compositional distribution.
However, the use of the conventional metallocene catalysts leads to production of polyolefin having the molecular weight distribution of about 2 to 3, consequently with a limitation in preparing a polyolefin with a wide range of properties.